Heat Diode Paves the Way For Thermal Computing

October 9, 2009

Heat Diode Paves the Way For Thermal Computing

Japanese team unveils the first diode that allows a heat current to travel in one direction but not the other

There’s no escaping the insidious effects of heat in microchips.
But there may now be a way of controlling it. Wataru Kobayashi at Waseda University in Japan and a few friends
have built a rectifier that allows a heat current to travel in one
direction but not the other.

For some time, researchers have
predicted that thermal rectifiers would be possible with materials which have
thermal conductivities that change with temperature. The trick is to
find a material with a high thermal conductivity at low temperatures
and a low thermal conductivity at high temperatures, and then to marry it
with a material with exactly the opposite characteristic.

Kobayashi and co found just such a match in two types of
perovskite cobalt oxides (LaCoO3 and La0.7Sr0.3CoO3). Glued together,
they form a diode-like device that allows a heat current to pass in
one direction but not the other.

That’s impressive because it’s the first time anybody has
demonstrated heat rectification in a bulk solid (it’s been done with
individual electrons in superconductors and in single nanotubes).

One obvious application is in heat sinks for microchips but some
significant improvements will be needed to carry the kind of heat
currents involved.

But Kobayashi and co have bigger prey in mind. They say: ”
Owing to the controllability of the heat current, the thermal
rectifier can be utilized for future practical application such as a
thermal transistor, thermal logic gates, and a thermal memory.”

What they don’t say is how thermal information processing might be
used. Presumably in places where electrical power is hard to come by and
where excess heat would otherwise go to waste. Thinking caps on.